The present invention relates to the field of cable splicing in high-voltage environments and in particular to the placement of a premolded high-voltage connector or other removable or permanent electrical insulating device over a high-voltage cable.
The need for splicing high-voltage power cable is often encountered in the power service industry. For example, splicing may be required either due to damage to an existing cable caused by digging during construction or other like activities. In addition, the need for high-voltage cable splicing may arise due to additional cable connection requirements as a result of residential expansion and increasing energy demands. Unlike the splicing of low-voltage devices, which may be accomplished with the use of simple connectors with minimal insulation, (frequently constructed of copper, aluminum and like components) high-voltage devices require splices which must maintain proper voltage grading, electrical insulation and water tightness. To achieve these requirements, the art of premolded high-voltage splicing may include the use of one, two, three or more insulated members. In addition, a tight fitting rubber member or sleeve may also cover the cable member connections. Due to the fact that the sleeve is generally manufactured of one diameter, cable adapters may be employed to accommodate a broad range of cable diameters. Therefore, in combination, the insulated members, sleeves and cable adapters secure the spliced region, thereby providing for protection against water seepage into the connection. In addition, this type of assembly allows the cable-to-cable splice to achieve the desired voltage and insulation demands. Such a fitting requires a careful, and often timely installation process, which involves the connection of opposing cable members to, and/or the placement of cable adapters over the cable insulation. Cable adapters or cable members are then connected to one another, or to other connector components, to provide a successful splice. It is further known in the art to require additional components to be installed on-site for securing opposing cable adapters or cable members to one another. As a result, as the number of additional installation components increase, more assembly time may be required in the field, thereby effecting the efficiency of the splicing operation.
For a successful splice, the cable members must fit securely within the corresponding splice components. Thus the inside diameter of the splice component is generally designed to be smaller than the outer diameter of each corresponding cable member (i.e., commonly referred to as the xe2x80x9cinterference fitxe2x80x9d.) To insure a snug fit, lubricant must be applied along the outside of the cable members and/or the inside of the cable adapters to assist in the installation process as the cable adapters are pulled over the corresponding cable members. However, difficulty may arise when a prepared or chamfered cable is inserted within a lubricated cable adapter. Specifically, upon insertion of the cable within the lubricated cable adapter, the chamfered cable acts to collect the useful lubrication from the inner portions of the cable adapter. Also, the interference fit acts to collect the lubrication from the outer portions of the cable thereby reducing the effectiveness of the lubrication. By removing the desired lubrication, it becomes extremely difficult to properly assemble the spliced cable member. In order to assist in the cable splicing operation it has become known in the art to use a wedge-shaped device to assist in drawing the chamfered cable through the cable adapter. Specifically, an adapter wedge, or mandrel, may be used to stretch the internal portions of the cable adapter to assist in drawing the chamfered cable through the cable adapter. By providing a wedge shaped device to assist in the assembly of the spliced members, lubricant may also be dispersed along the inner length of the spliced area (i.e., lubricant may be placed on the cable insulation, within the inner diameter of the cable adapter and on the wedge), thereby providing a void-free interface between the interior surfaces of the assembly. In addition, the void-free interface may further provide a resilient barrier against the ingress of moisture into the spliced region. However, adapter wedges or mandrels known in the art also remove and limit the usefulness of lubrication by creating excessive deposits of the lubrication at the base of the wedge as the splice is assembled. Specifically, the present wedges utilized in the art do not provide an adequate means for prevention of the removal of the lubricant during assembly. For example, based on the mechanical configuration and the designs of the prior art adapter wedges (i.e., linearly-tapered hollowed cylindrical cone), most, if not all of the lubricating substance is often removed from the cable members and cable adapters upon the placement of the wedge. At the circumference of the conical base, deposits of the lubricating substance form thereby rendering the lubricating substance useless by failing to provide a lubricating source at the points of contact between the adapter wedge and the cable adapter. Therefore, it becomes extremely difficult for lineman to complete the splice. The improper lubrication may lead to the use of excessive force by a lineman when affixing the adapter over the cable, which may lead to improper installation. As a result of this timely and difficult splicing process, additional and unnecessary labor costs may be incurred in the field.
Numerous disclosures are known in the art that attempt to deal with the splicing inconveniences encountered. Many of these disclosures and modes of splicing may be compatible with the present invention; however, these disclosures fail to provide the effective splicing components as presented in the present disclosure. Specifically, it is contemplated that any premolded splicing connection comprising an interference fit may be compatible with the present disclosure. For example, Fallot U.S. Pat. No. 3,980,374 teaches of a separable splice connector for use with 15 to 25 kilovolts and 600 amperes of current. The connector employs a unitary splice body assembly. The splice body assembly is constructed of molded elastic material and may be utilized for providing a straight splice. Therefore, it is foreseeable that the use of the adapter wedge employed in the present invention may be utilized in conjunction with the apparatus set forth in Fallot. However, Fallot fails to disclose the use of an adapter wedge for inserting the cable members within the corresponding cable adapters providing a secure fit. Therefore, there exists a need for an apparatus and method which provides a secure splice allowing for ease in operation, by allowing for a natural secure fit between cable members and splice components.
A second apparatus, comprising a pre-molded high voltage splice that may be compatible with the present invention, is disclosed in Lien U.S. Pat. No. 5,041,027. Lien discloses a system for electrically connecting a first power cable end to a second power cable end. The splice system comprises a first probe adapted to be electrically connected to the first power cable end and a second probe adapted to be electrically connected to the second power cable end and a cable splice. The cable splice further comprises two ends wherein a first female contact assembly is adapted to engage with the first probe and a second female contact assembly is adapted to engage with the second probe thereby forming a splice. However, Lien fails to disclose an apparatus comprising a mechanical configuration, which is effective for assisting in splicing high-voltage cables, that controls the removal of a lubricating substance. In addition, Lien fails to disclose an apparatus that allows for a dielectric sealant to be dispersed along the inner length of a cable adapter thereby providing a void-free bond between the surfaces of the cable member and cable adapter thereby providing ease in assembly. Furthermore, Lien fails to disclose a simplified method for providing an effective cable splice.
Luzzi U.S. Pat. No. 5,570,497 teaches of an apparatus and method for providing a linearly tapered mandrel for use with the insertion of a cable member through a premolded expandable product. The premolded expandable product has an initial inner radius approximately equal to the outer radius of the cable member. Upon forcing the linearly tapered mandrel inside the premolded expandable product the product stretches and a clamp maintains the product""s stretched position. The unit can then be used onsite for immediate installation whereby a cable can then be inserted into the stretched premolded expandable product. Subsequently, upon releasing the clamp, the product returns to its original position for a snug fit around the inserted cable. However, Luzzi fails to disclose a simplified method and apparatus for drawing a prepared cable through a cable adapter that does not require the use of additional onsite tools. In addition, Luzzi fails to disclose a method for controlling the removal of lubricant within a splice apparatus.
Numerous other systems and splicing mechanisms are known and utilized in the art. However, none of the currently employed systems provide for ease of application in creating an effective splice. For example, numerous systems are known that expand the inner diameter of the cable adapter or other cable splicing connectors by employing the use of complex tools onsite. These systems, demanding complex tool requirements, have proven to be costly for on-site applications. In addition, these systems, often employing some type of dielectric compound or lubricating substance tend to remove the lubricating substance when a cable is affixed within an apparatus. This type of inefficient design tends to make the performance of this type of splicing unduly time-consuming resulting in increased labor time and cost.
In other known systems, a stretching device may be employed for expanding the interior circumference of an adapter device. In these types of systems, upon placing a lubricated cable member within a premolded expandable product, the lubrication is completely removed from the outside of the cable member and the inner portion of the product if the product is not adequately stretched and held in place. Additionally, if the premolded expandable product is kept stretched for a long period of time it may incur damage and possibly take a permanent set, making it prone to faults and defects in construction.
In other known systems in the art a user may place lubrication on the cable members and lubricate a linearly tapered mandrel prior to the insertion of the cable into the premolded expandable product. However, the designs of mandrels in the art cause the lubrication to collect in the front end and back end of the cable adapter thereby removing the lubrication from the inside of the premolded expandable product as the mandrel is guided through the product. As a result of this loss of lubrication, installation becomes extremely difficult and in some cases impossible. Therefore, there exists a need in the art for an invention to provide a means for the uniform application of lubrication throughout an entire inner portion of a premolded expandable product. Furthermore, it is desirable to provide a simplified apparatus for high voltage splicing, requiring minimal additional tools, which allows a cable adapter to be placed over a cable member, requiring limited force for assembly. In addition, it is desirable to provide an apparatus that eliminates excessive assembly time onsite, limits the stress on the cable components and minimizes the risk of injury of a lineman during assembly by utilizing the applied lubricant instead of removing the lubricant as the cable adapter is fixed over a cable member.
Thus, their exists a need for an invention which resolves the limitations of the prior art by providing a suitable means for drawing a cable adapter over a cable splicing apparatus which does not eliminate the usefulness of the lubrication product between the inner surface of a premolded cable apparatus and the outer surface of a cable member.
The present invention provides a method and apparatus for preparing an effective cable splice providing uniform distribution of lubrication between cable members and joint components in high-voltage cable splices.
The present invention comprises a novel, uniquely tapered adapter wedge, or mandrel, further comprising longitudinally placed ribs. In the preferred embodiment of the present invention, the mandrel includes a cylindrical extended end with a radius approximately equal to the inner radius of a premolded expandable product in its relaxed state. In addition, the mandrel is tapered generally throughout its length as its radius gradually increases. Ribs protrude sufficiently outward from the mandrel""s center, dispersed longitudinally around the circumference of the outside of the mandrel.
To begin the cable splice, the mandrel, coated with a lubricant (i.e., non-hydrocarbon based lubricants or hydrocarbon based lubricants depending on the material properties of the splice components), is inserted over one end of a cable. The lubricated cable adapter may be lubricated by any known substances common in the art, in addition to those substances not yet contemplated. For example, it is known in the art that silicone grease compounds may prove useful in this type of application when hydrocarbon based materials are utilized. The cable adapter may then be drawn over the mandrel. As it enters, the mandrel stretches the inside of the cable adapter and the lubrication is transferred from the mandrel to the inner lining of the cable adapter. As the mandrel passes within the cable adapter, the longitudinally placed ribs on the outside of the mandrel serve to prevent the mandrel from wiping away and collecting the lubricant thereby maintaining a significant portion of lubrication within the regions displaced between the ribs. Although the preferred embodiment provides one design that is useful for maintaining the lubrication, it is foreseeable that numerous designs of the adapter wedge may be developed which may employ a broad range of characteristics useful for maintaining the desired lubrication within the joint. For example, it is foreseeable that designs may include any of a series of numbers of ribs, ribs of varying dimensions and shapes, raised ribs, recessed ribs, recessed dimples, convex protrusions, concave depressions or other similar designs. Upon the mandrel""s exit from the opposite end of the cable adapter, the cable remains positioned inside the lubricated cable adapter forming a tight fit between the cable and cable adapter. The tight fit around the cable member provides a barrier thereby thwarting the ingress of moisture. The cable adapter may then be slid back and forth over the cable member to allow for easy positioning adjustments during splicing.
Therefore, it is an object of the present invention to provide an effective system for high-voltage cable splicing and high-voltage cable termination.
It is a further object of the present invention to provide a means for maintaining a layer of lubrication on the inside of a cable adapter or other premolded expandable product.
In addition, it is an object of the present invention to provide a means for preventing the removal of lubrication within a cable adapter while the cable adapter is stretched during a splicing operation.
It is still a further object of the present invention to provide a means for maintaining a layer of silicone lubricant between the outside of a cable member and the inside of a cable adapter or other premolded expandable product while the adapter is guided along the surface of the cable member.
In addition, it is an object of the present invention to provide a means for maintaining a layer of silicone lubricant between the outside of a cable member and the inside of a cable adapter allowing for fine adjustment of the splice apparatus.
It is also an object of the present invention to provide a means for maintaining a layer of silicone lubricant between the outside of a cable and the inside of a cable adapter or other premolded expandable product wherein the premolded expandable product is not stretched for a long period of time and does not require clamps or other like specialized tools.
It is, therefore, an object of the present invention to provide a uniquely tapered mandrel with longitudinally positioned ribs to provide a means of maintaining a distribution of silicone lubricant between the outside of a cable and the inside of a cable adapter or other premolded expandable product.